Browsing by Subject "Orientation"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Artists for life: a proposal to increase the retention of first-year undergraduate students in the Texas Tech University Department of Theatre and Dance(2007-05) Scheckel, Beth; Adair, Aaron; Durham, GenevieveWhy do students abandon theatre or dance programs within or shortly after their first year of college? How does a department identify the factors that keep undergraduate students in the same major throughout their college careers? Once these factors are identified, how does a department implement improved strategies for retaining its students? How can a department, in conjunction with the university, best support undergraduate students to achieve a balance of success in academics, extracurricular activities, and personal matters? I propose a program for the Texas Tech University Department of Theatre and Dance that will improve the retention of its first-year undergraduate majors through increased student knowledge of department policies and procedures; increased support from faculty, staff, and successful majors; and increased awareness and access of campus resources.Item Controlling neural cell behavior with electric field stimulation across a conductive substrate(2012-12) Nguyen, Hieu Trung 1980-; Schmidt, Christine E.Electrical stimulation of tissues induces cell alignment, directed migration, extended processes, differentiation, and proliferation, but the mechanisms involved remain largely unknown. To reveal effects of electric fields (EF) through the media on cell behavior, voltage (7.45 – 22 V), current density (36 – 106 mA/cm2), duration (2 – 24 hrs), and alternating currents (AC, 2 – 1000 Hz) were varied independently when exposed to cell cultures. It was determined that current density and duration are the primary attribute Schwann cells respond to when an EF is applied through the media. This implies that the number of charges moving across the cell surface may play a key role in EF-induced changes in cell behavior. Identical conditions were used to stimulate cells grown on the surface of a conductive substrate to examine if a scaffold can provide structural and EF cues. The effects of an EF through the substrate were examined by placing a protein gel on the surface during stimulation and observing the morphology of subsequent cell cultures and the physical topology of the gel. EFs were shown to create Ca2+ redistribution across gels and subtle changes in collagen I fibril banding. Stimulated gels were able to induce perpendicular Schwann cell alignment on newly seeded cultures days after initial EF exposure, and the cell response decreased when seeded at longer times, indicating the effects of EF on the matrix environment has a relaxation time. These findings were then integrated into a biodegradable, electrically conductive polypyrrole-poly-ε-caprolactone polymer developed by collaborators. Dorsal root ganglia placed in matrix gels on top of conducting polymer exhibited significantly longer axons when stimulated with DC and AC signals. The overall results demonstrate that EFs have a significant effect on the extracellular environment. The broad implication of this data grants researchers with the ability to physically and metabolically control cell behavior with EFs, including improved wound healing or reduced cancer metastasis.Item Design, synthesis, and engineering of advanced materials for block copolymer lithography(2015-05) Durand, William John; Willson, C. Grant, 1939-; Ellison, Christopher J.; Bonnecaze, Roger T; Truskett, Thomas M; Akinwande, DejiBlock copolymers (BCPs) are an attractive alternative for patterning applications used to produce next-generation microelectronic devices. Advancements require the development of high interaction parameter χ BCPs that enable patterning at the sub-10 nm length scale. Several organosilicon BCPs were designed to both enhance χ and impart an inherent etch selectivity that facilitates pattern transfer processes. Increasing the BCP silicon content both increases χ and bolsters the etch resistance, providing a pathway to designing new high-χ materials. Unfortunately, the BCPs investigated are not amenable to thermal annealing because the organosilicon block preferentially segregates to an air/vacuum interface and drives orientation parallel to the surface. A series of spin-coatable, polarity-switching top coats (as well as other strategies) were developed to provide a “neutral” top interface and promote the perpendicular orientation of BCP domains. In addition, a methodology for evaluating the neutral condition, relying on thickness quantization and the corresponding wetting behavior (i.e. island/hole topography) of lamellae. The top coat strategy was demonstrated for several BCP systems, and perpendicular structures can successfully be etched on commercial tools and be transferred into underlying substrates. The interaction parameter χ was evaluated using two methods to compare the performance of several BCPs: the order-disorder transition (ODT) of symmetric diblock copolymers, and the absolute scattering profile of a disordered BCP melt. Both methods, while severely limited for quantitative comparison, indicate trends towards higher χ with additional appended polar and organosilicon functional groups. Furthermore, the pattern fidelity is shown to be a function of the overall BCP segregation strength. The free energy of confined lamella was modeled algebraically to produce response surface plots capable of identifying process conditions favorable for perpendicular orientation. Thickness independent perpendicular orientation is only favorable using two neutral interfaces. Incommensurate film thicknesses are the most favorable, with commensurability conditions dependent on the wetting behavior at each interface. The modeling was supplemented with an extensive body of thin film experimental work that qualitatively agrees well with the above conclusions.Item Effect of downscaling copper interconnects on the microstructure revealed by high resolution tem orientation mapping(2011-12) Kameswaran, Jai Ganesh, 1983-; Ferreira, Paulo J. S. G.; Ho, Paul S.; Rabenberg, Llewellyn K.; Krishnan, Srikanth; Rhee, Seung-Hyun; Gall, MartinThe scaling required to accommodate faster chip performance in microelectronic devices has necessitated a reduction in the dimensions of copper interconnects at the back end of the line. The constant downscaling of copper interconnects has resulted in changes to the microstructure, and these variations are known to impact electrical resistivity and reliability issues in interconnects. In this work, a novel electron diffraction technique called Diffraction Scanning Transmission Electron Microscopy (D-STEM) has been developed and coupled with precession electron microscopy to obtain quantitative local texture information in damascene copper lines (1.8 \mu m to 70 nm in width) with a spatial resolution of less than 5 nm. Misorientation and trace analysis has been performed to investigate the the grain boundary distribution in these lines. The results reveal strong variations in texture and grain boundary distribution of the copper lines upon downscaling. 1.8 \mu m wide lines exhibit strong <111> normal texture and comprise large bamboo-type grains. Upon downscaling to 180 nm, a {111} <110> biaxial texture has been observed. In contrast, narrower lines of widths 120 nm and 70 nm reveal sidewall growth of {111} grains and a dominant <110> normal texture. The fraction of coherent twin boundaries also reduces with decreasing line width. The microstructure changes from bamboo-type in wider lines to one comprising clusters of small grains separated by high angle boundaries in the vicinity of large grains. The evolution of such a microstructure has been discussed in terms of overall energy minimization and dimensional constraints. Finite element analysis has been performed to correlate misorientations between grains and local thermal stresses associated with stress migration. Effect of variations in the copper interconnect microstructure on electromigration flux divergence has also been discussed.Item Glass as a Building Element ? A Sustainable Approach: A Study of an Existing Academic Building(2011-02-22) Jori, Swapnil ShriramIn the aspects of global sustainability, buildings are known to be one of the largest energy consumers. Though sustainable building construction through technological advances is helping in achieving environment friendly buildings, a considerable amount of energy is also being consumed by existing buildings. While many factors at all different stages of building life are responsible for this, the building material is one of the most important considerations. Glass being the most sensitive building material can lead to high energy consumption in the building if used in an improper way. This study takes this factor into account, and tries to investigate the potential of energy savings in buildings through the simple and basic considerations in design. An energy analysis model of an existing academic building in College Station, Texas was developed using Design Builder computer simulation software. This model was then analyzed for the total amount of energy consumption in the base case. The existing building model was then modified by replacing the glass used for external fenestrations. Latest building codes and standards for the site location, glass properties, and parametric simulation results were taken into consideration. Again the model was simulated for annual energy consumption and the results are noted. This formed the first option for the retrofitting scenario. A hypothetical redesign scenario was also established in which the revision of building orientation was taken into consideration. The building was re-oriented to suit the weather conditions and recommendations by Advanced Energy Design Guidelines (30 percent energy savings over ASHRAE Standard 90.1-1999). The building was then simulated for annual energy consumption. A comparative analysis was performed between the three cases and the study concluded by showing 23 percent savings in the annual fuel consumption, 23.35 percent reduction in CO2 emission of the building and 25 percent reduction in annual solar heat gain under Modified case 1. Modified case 2, however, did not show any further savings due to the form of the building (almost square). However, modified case 1 settings emitted 31.8 percent more CO2 over the Energy Star office building in Texas. This methodology sets up a set of guidelines which can be followed while investigating a building for minimum annual energy consumption.